Intrusion detector



March 29, 1966 H. J. SMITH INTRUSION DETECTOR Filed April 1, 1964 m y MM N V M Wm. W a w Q Mnw e,\ o u sE u WY u N NR] 0 J QN m k Mk M645? 7 NNN AQN .SQN.

N- Q N 2%? United States Patent 3,243,797 INTRUSION DETECTOR Harvey J. Smith, St. Louis Park, Minn., assignor t0 Honeywell Inc., a corporation of Delaware Filed Apr. 1, 1964, Ser. No. 356,487 4 Claims. (Cl. 340274) This invention is concerned with security apparatus and more particularly with an improved perimeter detection system utilizing a taut filament detector device which includes motor balanced temperature compensation means.

The use of a taut filament or wire in a perimeter detection system is well known in the art. It is also well known that such a device can be used to give an alarm when the tension of the wire is either increased or decreased, that is when the wire is either deflected or broken. What is not well known in the art, though various methods have been tried, is an accurate way to compensate for minor increases and decreases in the length of the wire due to temperature variation. This invention utilizes a method of sensing the rate of change of the length of the wire to determine whether the change is due to intrusion or to temperature. If there is merely a gradual change due to a change in temperature then a motor rebalance system will drive the control or sensing apparatus to a position wherein it will be as sensitive to intrusion as it was previous to the temperature change. It the change is of a rate to indicate intrusion, the rate sensor will sound an alarm immediately.

It is therefore an object of this invention to provide a taut filament detector with improved temperature compensation means.

It is a further object of this invention to provide a temperature compensated taut filament detector which will maintain a constant sensitivity to intrusion at various temperatures.

These and other objects of the invention will become apparent upon consideration of the accompanying claims, specification and drawing, of which:

The single figure is a representation of a taut wire detector including temperature and sensitivity compensating means.

Referring now to the drawing there is disclosed a taut filament or wire 11 having one end connected to one end of a plate 20 at a point 12. The wire 11 then passes through a plurality of eyelets or guides such as 13, 14 and 15 to connect to one end of a heavy spring 18. The other end of spring 18 is connected to a support 19.

The other end of plate 20 is connected at point 29 to one end of a lighter spring 30. The other end of spring 30 is connected to a support 31.

The plate 20 is slideably mounted to a support 26 by means of studs or screws 23 and 24 inserted through, respectively, slots 21 and 22. A portion 25 of one edge of plate 20 is inclined or beveled so as to form an oblique angle with slots 21 and 24.

There is also shown a mount or carriage 40 which is slideably mounted to a support 48 by means of studs or screws 46 and 47 inserted through slots 44 and 45. Carriage 40 is connected at a point 53 a filament 51 which .is adapted to be wound on a drum 52. Rotation of drum 52 is controlled by a motor 50. The carriage 40 is also connected at a point 54 to one end of a spring 55. The other end of spring 55 is connected to a support 56. Mounted on carriage 40 is a support 41. Attached to support 41 by means of a spring 42 is a roller or slider 43, yieldingly biased against beveled edge 25 by spring 42. Also mounted on carriage 40 are a first, single-pole, double-throw set of contacts comprising a common contact 60, a normally closed contact 61 and a normally open contact 62, and a second single-pole,

3,243,797 Patented Mar. 29, 1966 double-throw set of contacts comprising a common contact 63, a normally closed contact 64 and a normally open contact 65. Common contacts 60 and 63 are mechanically connected together by a yoke '70 and are actuated by movement of the yoke 70 caused by contact with spring 42 at an insulated point 71. Contact 60 is directly connected to a voltage terminal 72. Contact 61 is connected through a phase winding 78 of motor 50 to a voltage terminal 73. Contact 62 is connected through a phase winding 78 of motor 50 to a voltage terminal 73. Contact 62 is connected through a phase winding 79 of motor 50 t0 the voltage terminal 73. A capacitor 77 is connected between contacts 61 and 62. Contact 64 is connected to an alarm terminal 82. Contact 65 is also connected to alarm terminal 82. Contact 63 is connected to an alarm terminal 83.

In normal operation member 20 is positioned between light spring 30 and taut wire 11 such that member 20 will slide laterally when there is an extrinsic deflection of wire 11, or when there is a temperature caused contraction or expansion of Wire 11. In the case of the temperature caused changes, though the change in length of wire 11 will be small, there will be a sufficient change to cause an expansion or contraction of spring 30, which spring 30 is made light enough to yield to such small changes. Spring 18 is, on the other hand, a very heavy spring and will yield only when an extremely large deflection of wire 11 occurs. The purpose of the spring 18 therefore is only to protect the mechanism in cases of unusually large deflections, and it is apparent that spring 18 could be removed and wire 11 directly connected to support 19.

It can be seen that as member 20 slides laterally, by the means of slots 21 and 22 on studs 23 and 24, that the roller or slider 43 will, due to the force from spring 42, slide up or down the inclined edge 25. It can also be seen that movement of slider 43 will cause spring 42 to increase or decrease its pressure at point 71 on yoke 70, thus commutating contacts 60 and 63. It should be noted that spring 42 could be a member, other than a spring, pivotally mounted to support 41, and that the necessary biasing could be achieved through the action of contact arms 60 and 63. Thus as slider 43 is allowed to move down the beveled edge the pressure at point 71 is decreased and normally closed contact 61 makes with common contact 60. It is important to note at this point that the spacing between the common contact 60 and contacts 61 and 62 is less than the space between common contact 63 and contacts 64 and 65. Thus contacts 60 and 61 will make before contacts 63 and 64 make. This closure of contacts will cause a voltage to flow from voltage terminal 72 through contacts 60 and 61 through phase winding 78 of motor 50 and back to voltage terminal 73. This current will cause motor 50 to turn the drum or reel 52 to take-up filament 51, which in turn causes a lateral displacement of carriage 40. In the case given where the slider 43 has been allowed to move down the inclined edge 25, the movement of carriage 40 will be in a direction against spring 55 which will thus cause roller 43 to again be centered in inclined edge 25. As the slider 43 reaches the center of inclined edge 25, contacts 60 and 61 will open and motor 50 will stop turning, thus causing the halting of the motion of carriage 40.

If the motion of member 20 is slow enough to allow the above described series of events to take place before there has been sufiicient commutation of contact 63 to allow closure with contact 64, then no alarm will be given. Indeed, motor 50 is designed to turn at a low rate, on the order of two revolutions per hour, and thus designed to correct the position of carriage 40 and slider 43 before an alarm can be sounded in those cases where the movement of member is occasioned by slow deflections, expansions, or contractions in wire 11, such as changes due to an increase or decrease in temperature.

It will be obvious that should the movement of member 20 be in the opposite direction, slider 43 would appear to move up inclined edge thus causing an increase of the pressure of spring 42 on yoke 70 through contact point 71. This would cause common contact 60 to make with contact 62, thus causing a current to flow from voltage terminal 72 through contacts 60 and 62, now through phase winding 79 of motor 50 and back through the voltage terminal 73. This current would cause motor 50 to turn in the opposite direction as previously described, causing drum 52 to unwind filament 51, thus allowing spring 55 to move carriage in the opposite direction to again center slider 43 on inclined edge 25. Should the motion of member 20 be sufficiently fast to allow contact 63 to make with contact 65 before a correction can be made on the position of slider 43, then an alarm would be given through the shorting of alarm contacts 82 and 83 by contacts 63 and 65.

It should be noted that the spring 18 and support 19 could be replaced by a weight to keep tension on wire 11, in which case the position of member 20 could be changed to a point where the greatest movement will occur with each change in the length or tension of the wire. Also, motor could be directly geared to carriage 40 removing the need for spring 55, and slider 43 could be a series of sliders or rollers on a plurality of edges on member 20. These combinations are pointed out to give an example of the many variations which could be built in keeping with the inventive idea of the device of this application.

It can be seen that this invention involves a new apparatus which will detect the rate of change of length of a taut wire, and the rate of change of the tension of a taut wire, and difierentiate between those rates of change due to temperature increases or decreases, and between those greater rates of change more likely to be caused by intrusion.

It will be obvious that the general principles herein disclosed may be embodied in many other embodiments widely different from that illustrated, without departing from the spirit of the invention as defined in the following claims.

What is claimed is:

1. In an intrusion detector including a taut filament detection system wherein the increase or decrease of tension of a taut filament actuates an alarm, the temperature compensation combination comprising:

first movable means connected intermediate the ends of a taut filament and adapted to move laterally along the axis of said filament, said first means including an edge inclined obliquely with respect to the axis of said filament;

second movable means yieldingly biased against said inclined edge and adapted to move along said inclined edge as said first means moves; switch means including first actuated contacts and later actuated contacts, said first and later actuated contacts yieldingly biased against said second means so as to be actuated by movement of said second means;

mounting means for said second means and said switch means;

position control means;

means connecting said mounting means to said position control means so that said mounting means is movable in a direction parallel to the direction of movement of said first movable means;

circuit means connecting said first actuated contacts in electrical circuit with and in controlling relation to said position control means;

and further circuit means connecting said later actuated contacts in electrical circuit With and in controlling relation to alarm means.

2. A temperature compensating taut filament intrusion detector comprising:

a slideably mounted member;

first spring means connecting a first end of said member to a support;

means including a predetermined length of filament means connected to an opposite end of said member so as to place said filament means under tension;

an inclined edge on said member, said edge inclined obliquely to the axis of the direction of slide of said plate;

a second slideably mounted member;

a position control motor;

means connecting said second member to said position control motor;

slider means mounted on said second member and yieldingly biased to slide along said inclined edge;

and switch means mounted on said second member and operably connected to said slider means, said switch means including first and second sequentially operated contacts, said first contacts connected in controlling relation to said position control motor, said second contacts connected in controlling relation to alarmmeans.

3. Temperature compensation for a taut filament device comprising:

a first member connected intermediate the ends of a yieldingly biased taut wire filament, said first member including an edge inclined obliquely with respect to the axis of said filament;

position control means;

a second member connected to said position control means, said second member adapted to move in a direction parallel to the axis of said filament when moved by said position control means;

a third member mounted on said second member and yieldingly biased against said inclined edge;

and switch means mounted on said second member, said switch means yieldingly biased against said third member and including first actuated contacts operably connected to said position control means and later actuated contacts operably connected to alarm means.

4. A temperature compensating taut filament intrusion detector comprising:

a plate, said plate mounted by mounting means, said mounting means adapted to confine said plate to movement along a single line;

an inclined edge on said plate, said edge inclined obliquely with respect to said single line of movement of said plate;

a spring connecting one end of said plate to a support;

means including a filament connecting the other end of said plate to another support;

a carriage, said carriage mounted by further mounting means, said further mounting means adapted to confine said carriage to movement along a further line parallel to said single line;

a reversible motor operably connected to said carriage to control the direction of movement of said second plate along said further line;

a shaft connected to said carriage;

a second spring connected to said shaft; slider means connected to said second spring and yieldingly biased against said inclined edge by said second spring;

switch means mounted on said carriage including first and second contacts adapted to be sequentially operated by movement of said slider along said inclined edge;

circuit means connecting said first contacts to control said motor;

and further circuit means connecting said second contacts to control alarm means.

(References on following page) 5 6 References Cited by the Examiner FOREIGN PATENTS UNITED STATES PATENTS 1,253,355 2/1961 France. 2,342,034 2/ 1944 Beakes. 2 42 290 9 947 Peck 34o 25 X NEIL READ: Prlmary Exammer- 3,184,730 5/1965 Irish 340-274 X 5 R. M. GOLDMAN, Assistant Examiner. 

1. IN AN INTRUSION DETECTOR INCLUDING A TAUT FILAMENT DETECTION SYSTEM WHEREIN THE INCREASE OR DECREASE OF TENSION OF A TAUT FILAMENT ACTUATES AN ALARM, THE TEMPERATURE COMPENSATION COMBINATION COMPRISING: FIRST MOVABLE MEANS CONNECTED INTERMEDIATE THE ENDS OF A TAUT FILAMENT AND ADAPTED TO MOVE LATERALLY ALONG THE AXIS OF SAID FILAMENT, SAID FIRST MEANS INCLUDING AN EDGE INCLINED OBLIQUELY WITH RESPECT TO THE AXIS OF SAID FILAMENT; SECOND MOVABLE MEANS YIELDINGLY BIASED AGAINST SAID INCLINED EDGE AND ADAPTED TO MOVE ALONG SAID INCLINED EDGE AS SAID FIRST MEANS MOVES; SWITCH MEANS INCLUDING FIRST ACTUATED CONTACTS AND LATER ACTUATED CONTACTS, SAID FIRST AND LATER ACTUATED CONTACT YIELDINGLY BIASED AGAINST SAID SECOND MEANS SO AS TO BE ACTUATED BY MOVEMENT OF SAID SECOND MEANS; MOUNTING MEANS FOR SAID SECOND MEANS AND SAID SWITCH MEANS; POSITION CONTROL MEANS; MEANS CONNECTING SAID MOUNTING MEANS TO SAID POSITION CONTROL MEANS SOT THAT SAID MOUNTING MEANS IS MOVABLE IN A DIRECTION PARALLEL TO THE DIRECTIN OF MOVMENT OF SAID FIRST MOVABLE MEANS; CIRCUIT MEANS CONNECTING SAID FIRST ACTUATED CONTACTS IN ELECTRICAL CIRCUIT WITH AND IN CONTROLLING RELATION TO SAID POSITION CONTROL MEANS; AND FURTHER CIRCUIT MEANS CONNECTING SAID LATER ACTUATED CONTACTS IN ELECTRICAL CIRCUIT WITH AND IN CONTROLLING RELATION TO ALARM MEANS. 